Lymphedema is swelling of the arm, hand, chest wall, back, or other body part caused by lymph fluid collecting in tissue after surgery, especially breast cancer surgery that removes underarm (axillary) lymph nodes. Edema is the medical term for swelling, so swelling caused by lymph fluid is "lymphedema."

Many doctors believe that lifting heavy objects with an arm at risk for lymphedema may cause lymphedema to develop. If lymphedema has already developed, many doctors also believe that lifting heavy objects may worsen it. A study suggests that a careful weight lifting program that starts with light weights and gradually increases after breast cancer surgery doesn't increase lymphedema risk and could possibly lower the risk of developing lymphedema. The results were presented at the 2010 San Antonio Breast Cancer Symposium (SABCS).

Lymph fluid normally drains from body tissues through the lymph nodes and lymph channels. If some lymph nodes and channels are removed or damaged during surgery, the lymph fluid may not drain properly and can collect in the tissues near the surgery site. The more lymph nodes that are removed, the greater the risk of lymphedema. Some research suggests that the risk of lymphedema is higher and any lymphedema that does develop is more severe in women who are overweight or obese. Radiation therapy and chemotherapy can increase the risk of lymphedema.

All of the women in this study, called the Physical Activity and Lymphedema (PAL) trial, had surgery to remove early-stage breast cancer and all the women had at least two lymph nodes removed. Because of the surgery, all the women were at risk for lymphedema or had already developed lymphedema in the arm on the side where the breast cancer was removed.

In this analysis, the researchers looked at 154 women in the PAL trial who didn't have lymphedema when the trial started. Half of the women made no changes to how they cared for their arms after surgery. The other half of the women took part in a weight lifting program made up of:

membership at a gym (mostly local YMCAs) working with trainers who took a special class on how to weight train the women

13 weeks of weight lifting classes designed specifically for women with lymphedema or at risk for it; the women started with very light weights (1 to 2 pounds) and gradually increased

a custom-fitted compression garment (a wrap that gently compresses the arm and hand) that was worn while weight lifting

After 1 year, the 134 women who completed the weight lifting program and follow-up were no more likely to develop lymphedema than the women who didn't participate in the weight lifting program.

Overall, 11% of the women who lifted weights developed lymphedema compared to 17% of the women who didn't lift weights.

This study looked at whether weight lifting would increase the risk of developing lymphedema. This study didn't look at whether weight lifting could reduce the risk of developing lymphedema after breast cancer surgery. Still, women who were at the highest risk of developing lymphedema (they had five or more lymph nodes removed) and lifted weights were 70% less likely to develop lymphedema compared to women at the highest risk who didn't lift weights:

About 7% of high-risk women who lifted weights developed lymphedema compared to 22% of high-risk women who didn't lift weights.

On average, women who lifted weights increased their body strength and decreased their body fat.

The same researchers who did this study did an earlier analysis of women in the PAL trial who were diagnosed with lymphedema when they started the study. They found that the women who lifted weights were more likely to have some easing of the lymphedema and less likely to have the lymphedema get worse compared to women who didn't lift weights. So contrary to popular belief, lifting weights didn't make existing lymphedema worse.

More research should be done with larger groups of women to see if gradually increasing weight lifting after breast cancer surgery can actually lower the risk of developing lymphedema.

These results suggest that the common recommendation to avoid strenuous use of an arm at risk for lymphedema after breast cancer surgery may not always make sense. Still, until we know more, it's probably good to be cautious. If you're scheduled for breast cancer surgery, be sure to ask your doctor about your risk of lymphedema and any steps you can take to lower that risk. After surgery, talk to your doctor about exercises and any activity restrictions that make the most sense for your unique situation. If you'd like to do strength training after surgery, you might want to ask your doctor about this study and ask for the name of a physical therapist who works with women who have lymphedema or are at risk for lymphedema.

Stay tuned to Breastcancer.org for the latest information on lymphedema and its treatment.